Soft robots can change their shapes actively or passively for safe human interaction and agile, robust and adaptive locomotion in complex environments. A soft robot can pass through a hole smaller than its body size using its shape-morphing ability. Passive or active deformation of soft robots enables a safe and gentle physical interaction with a human where their impact on the human is minimal due to their compliant body. This aspect is especially important for medical applications for safe and minimally invasive operation.
Actuation and locomotion methods of current robotic capsule endoscopes are primarily determined by the target gastrointestinal (GI) tract or other human body region in which they will be operated. For close to one-dimensional (1-D) tubular systems such as intestines and esophagus and legs, various type of actuation mechanisms have been proposed using, for example, on-board paddles, micro-motors or off-board magnetic linear or rotational actuation methods. In these approaches, although on-board actuation using micro-motors enables more portable operations, limited power source and limited space on such capsules limit their utility for long duration and less invasive operations.
For three-dimensional (3D) regions of the GI tract such as the stomach, wall-to-wall locomotion methods in a liquid filled environment or a sliding type of surface locomotion method in an inflated stomach have been described using mostly external magnetic actuation methods. In such magnetically actuated capsule endoscopes (MACEs), external magnetic fields are used to exert forces or torques on the internal magnet of the capsule remotely to navigate the capsule in 3D.
Although there have been many promising studies on MACEs and soft robotics, there are still many open issues. First, advanced diagnostic and therapeutic functional modules that are compatible to external magnetic actuation principles are not available yet. Next, precise 3D position control of the device on the tissue surface has not been addressed in detail yet. A robotic manipulator with a permanent magnet is sometimes used for this reason, but the locomotion can be discontinuous and unstable depending on the morphology and friction of the environment. Further, real-time position detection or estimation of MACE that is compatible to continuous magnetic actuation is challenging. To navigate a MACE to a desired position, it is essential to maintain an effective distance between external and internal magnets. Finally, possible tissue damage due to the excessive magnetic attraction (it is difficult to control the magnetic forces on the capsule precisely using external permanent magnet-based actuation) and edges on the capsule could be a safety issue, which has not been addressed in detail in the prior art. All current MACEs are made of rigid outer material, which might create very high stresses on the tissues during magnetic actuation.
To address above issues for the use of MACE's for 3D stomach applications, the present invention describes methods to integrate active capsule endoscopy with soft robotics. Thus, a magnetically actuated soft capsule endoscope (MASCE) is described, which has three novel features with compared to the prior art: 1) Its outside body is made of soft elastomers-based compliant structures. Such compliant structures can deform passively during the robot-tissue contact interactions, which makes the device safer and less invasive. 2) It can be actively deformed in axial direction using external magnetic actuation, which provides an extra degree of freedom that enables various advanced functions such as axial position control, drug releasing, drug injection, or biopsy. We also describe methods that allow the MASCE's shape to be changed from a cylindrical (pill-shape) shape to a spherical-like shape to anchor inside stomach for in situ passive or active drug delivery applications. 3) It navigates in 3D by rolling on the stomach surface which represents a new surface locomotion method inside the stomach. Here, the external attractive magnetic force is used to anchor the robot on a desired location, and the external magnetic torque is used to roll it to another location, which provides a stable, continuous and controllable motion.